In chute feeds and similar devices for collecting and densifying fibers to be fed as a batt to carding machines and the like, it is important that the batt have a uniform density to prevent defects being formed in the yarn that is ultimately produced from the batt.
Since the fiber normally flows to the chute in relatively loose tufts, it is common practice to provide some arrangement for compressing or densifying the fiber in the chute so that the fiber emerges as a batt. For example, Beukert U.S. Pat. No. 3,896,523, issued July 29, 1975, discloses a feeding device having an oscillating shaker plate or spanker plate that moves toward and away from an opposite fixed wall to densify the fibers in a generally uniform manner, the speed of oscillation of the plate being controlled by the rotational speed of the feed rollers which supply fiber thereto.
Compression of the fibers in a chute may also be obtained using a flow of pressurized air that acts to compress the fibers collected in the chute, and this pressurized air may be obtained from a bellow or a more complex air flow arrangement of the type disclosed, for example, in Husges U.S. Pat. No. 4,136,911.
Finally, it is also known that the flow of air used to carry fiber to a chute may be controlled by providing slots in the wall of the chute and using adjustable needles to vary the open portion of such slots as disclosed in Hecker U.S. Pat. No. 3,482,883.
When pressurized air flows into, through, and beyond the chute to compress the fibers it will pick up lint which must be separated from the air after it leaves the chute, thereby requiring additional filtering equipment or burdening the existing filtering equipment. Additionally, the forces imposed on the fiber by the air is generally uniform across the surface of the collected fiber, and if the level of fiber is uneven, the generally equal compression provided by the air may result in the collected fiber having an uneven density across its width. On the other hand, oscillating spanker plates avoid the problem of requiring additional air filtration, but the indiscriminate feeding of fiber tufts to the spanker plate may result in uneven fiber levels that will be compressed to different densities across the width of the spanker plate.
By contrast, the present invention provides a chute which does not require any additional air filtration while also improving significantly the uniformity of the fiber density as it leaves the chute in batt forms.